Alas sorry, that was fleeting.
I had just burnt the flash, stuck it in the RasPi, was going through the installs and had to install NR while the machine as residing in the RP 3B.
I did a double take on it and wondered what was going on.
As it was all happening on that machine, I didn't/couldn't log on here and post the question.
I guess now it is "water under the bridge". and yeah, sorry. I shouldn't have mentioned it.
But basically it was "command not found".
(Back story)
This is for a machine running on a RPZ(W) which was running 100% CPU load since I updated from ..... Jessie(?) to Buster. (2 versions back.)
Originally the machine (as is/was) was running 30% CPU.
It went to 100% ALL THE TIME.
This was done by doing the update to the existing. I think we've been there and had it mentioned here.
Anyway, as it failed I was flashing a new card from the online source.
Suffice to say I lost about 4 hours and achieved nothing. 
Still 100% CPU load.
